feat: add support for specifying an initial-network property

This network is the network that is associated with the container on creation. If specified, then the bridge network is not attached to the service.

Only a single initial network can be specified at this time.

README.md

@@ -44,6 +44,7 @@ mysql:logs <service> [-t|--tail] <tail-num-optional> # print the most recent log
 mysql:pause <service>                              # pause a running mysql service
 mysql:promote <service> <app>                      # promote service <service> as DATABASE_URL in <app>
 mysql:restart <service>                            # graceful shutdown and restart of the mysql service container
+mysql:set <service> <key> <value>                  # set or clear a property for a service
 mysql:start <service>                              # start a previously stopped mysql service
 mysql:stop <service>                               # stop a running mysql service
 mysql:unexpose <service>                           # unexpose a previously exposed mysql service
@@ -250,6 +251,25 @@ You can unlink a mysql service:
 dokku mysql:unlink lollipop playground
 ```
 
+### set or clear a property for a service
+
+```shell
+# usage
+dokku mysql:set <service> <key> <value>
+```
+
+Set the network to attach after the service container is started:
+
+```shell
+dokku mysql:set lollipop post-create-network custom-network
+```
+
+Unset the post-create-network value:
+
+```shell
+dokku mysql:set lollipop post-create-network
+```
+
 ### Service Lifecycle
 
 The lifecycle of each service can be managed through the following commands: